Thaw the frozen spinach and squeeze out as much moisture as possible using a clean kitchen towel or cheesecloth so patties don’t become soggy.
In a large bowl combine the ground turkey, Greek seasoning, egg, drained spinach, and crumbled feta; use your hands to mix until ingredients are evenly distributed.
Shape the mixture into 1/3-pound patties about 1 inch thick (this should make about 10 patties).
Heat a large skillet over medium heat and add half of the olive oil. When the oil is hot, add several patties without overcrowding the pan.
Cook the patties 4–5 minutes on the first side without moving them, then flip and cook another 4–5 minutes until internal temperature reaches 165°F (74°C).
Remove cooked patties and repeat with remaining oil and patties, or grill the patties 4–5 minutes per side until cooked through.
Serve the burgers on buns, in pitas, wrapped in lettuce, or over bowls as desired.
